/// <summary>
/// Computes the calculated value given a raw counter sample.
/// </summary>
public static float ComputeCounterValue(CounterSample oldSample, CounterSample newSample)
{
var newCounterType = (int)newSample.CounterType;
if (oldSample.SystemFrequency == 0)
{
if ((newCounterType != Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_RAW_FRACTION) &&
(newCounterType != Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_RAWCOUNT) &&
(newCounterType != Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_RAWCOUNT_HEX) &&
(newCounterType != Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_LARGE_RAWCOUNT) &&
(newCounterType != Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_LARGE_RAWCOUNT_HEX) &&
(newCounterType != Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_MULTI_BASE))
{
// Since oldSample has a system frequency of 0, this means the newSample is the first sample
// on a two sample calculation. Since we can't do anything with it, return 0.
return(0.0f);
}
}
else if (oldSample.CounterType != newSample.CounterType)
{
throw new InvalidOperationException("SR.MismatchedCounterTypes");
}
if (newCounterType == Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_ELAPSED_TIME)
{
return(GetElapsedTime(oldSample, newSample));
}
var newPdhValue = new Interop.Interop.Kernel32.PerformanceCounterOptions.PDH_RAW_COUNTER();
var oldPdhValue = new Interop.Interop.Kernel32.PerformanceCounterOptions.PDH_RAW_COUNTER();
FillInValues(oldSample, newSample, ref oldPdhValue, ref newPdhValue);
LoadPerfCounterDll();
var pdhFormattedValue = new Interop.Interop.Kernel32.PerformanceCounterOptions.PDH_FMT_COUNTERVALUE();
var timeBase = newSample.SystemFrequency;
var result = Interop.Interop.PerfCounter.FormatFromRawValue((uint)newCounterType, Interop.Interop.Kernel32.PerformanceCounterOptions.PDH_FMT_DOUBLE | Interop.Interop.Kernel32.PerformanceCounterOptions.PDH_FMT_NOSCALE | Interop.Interop.Kernel32.PerformanceCounterOptions.PDH_FMT_NOCAP100,
ref timeBase, ref newPdhValue, ref oldPdhValue, ref pdhFormattedValue);
if (result != Interop.Interop.Errors.ERROR_SUCCESS)
{
// If the numbers go negative, just return 0. This better matches the old behavior.
if (result == Interop.Interop.Kernel32.PerformanceCounterOptions.PDH_CALC_NEGATIVE_VALUE || result == Interop.Interop.Kernel32.PerformanceCounterOptions.PDH_CALC_NEGATIVE_DENOMINATOR || result == Interop.Interop.Kernel32.PerformanceCounterOptions.PDH_NO_DATA)
{
return(0);
}
throw new Win32Exception(result, SR.Format(SR.PerfCounterPdhError, result.ToString("x", CultureInfo.InvariantCulture)));
}
return((float)pdhFormattedValue.data);
}
// This method figures out which values are supposed to go into which structures so that PDH can do the
// calculation for us. This was ported from Window's cutils.c
private static void FillInValues(CounterSample oldSample, CounterSample newSample, ref Interop.Interop.Kernel32.PerformanceCounterOptions.PDH_RAW_COUNTER oldPdhValue, ref Interop.Interop.Kernel32.PerformanceCounterOptions.PDH_RAW_COUNTER newPdhValue)
{
var newCounterType = (int)newSample.CounterType;
switch (newCounterType)
{
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_COUNTER:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_QUEUELEN_TYPE:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_SAMPLE_COUNTER:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_OBJ_TIME_TIMER:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_OBJ_TIME_QUEUELEN_TYPE:
newPdhValue.FirstValue = newSample.RawValue;
newPdhValue.SecondValue = newSample.TimeStamp;
oldPdhValue.FirstValue = oldSample.RawValue;
oldPdhValue.SecondValue = oldSample.TimeStamp;
break;
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_100NS_QUEUELEN_TYPE:
newPdhValue.FirstValue = newSample.RawValue;
newPdhValue.SecondValue = newSample.TimeStamp100nSec;
oldPdhValue.FirstValue = oldSample.RawValue;
oldPdhValue.SecondValue = oldSample.TimeStamp100nSec;
break;
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_TIMER:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_TIMER_INV:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_BULK_COUNT:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_LARGE_QUEUELEN_TYPE:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_MULTI_TIMER:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_MULTI_TIMER_INV:
newPdhValue.FirstValue = newSample.RawValue;
newPdhValue.SecondValue = newSample.TimeStamp;
oldPdhValue.FirstValue = oldSample.RawValue;
oldPdhValue.SecondValue = oldSample.TimeStamp;
if (newCounterType == Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_MULTI_TIMER || newCounterType == Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_MULTI_TIMER_INV)
{
// this is to make PDH work like PERFMON for
// this counter type
newPdhValue.FirstValue *= (uint)newSample.CounterFrequency;
if (oldSample.CounterFrequency != 0)
{
oldPdhValue.FirstValue *= (uint)oldSample.CounterFrequency;
}
}
if ((newCounterType & Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_MULTI_COUNTER) == Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_MULTI_COUNTER)
{
newPdhValue.MultiCount = (int)newSample.BaseValue;
oldPdhValue.MultiCount = (int)oldSample.BaseValue;
}
break;
//
// These counters do not use any time reference
//
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_RAWCOUNT:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_RAWCOUNT_HEX:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_DELTA:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_LARGE_RAWCOUNT:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_LARGE_RAWCOUNT_HEX:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_COUNTER_LARGE_DELTA:
newPdhValue.FirstValue = newSample.RawValue;
newPdhValue.SecondValue = 0;
oldPdhValue.FirstValue = oldSample.RawValue;
oldPdhValue.SecondValue = 0;
break;
//
// These counters use the 100 Ns time base in thier calculation
//
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_100NSEC_TIMER:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_100NSEC_TIMER_INV:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_100NSEC_MULTI_TIMER:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_100NSEC_MULTI_TIMER_INV:
newPdhValue.FirstValue = newSample.RawValue;
newPdhValue.SecondValue = newSample.TimeStamp100nSec;
oldPdhValue.FirstValue = oldSample.RawValue;
oldPdhValue.SecondValue = oldSample.TimeStamp100nSec;
if ((newCounterType & Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_MULTI_COUNTER) == Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_MULTI_COUNTER)
{
newPdhValue.MultiCount = (int)newSample.BaseValue;
oldPdhValue.MultiCount = (int)oldSample.BaseValue;
}
break;
//
// These counters use two data points
//
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_SAMPLE_FRACTION:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_RAW_FRACTION:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_LARGE_RAW_FRACTION:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_PRECISION_SYSTEM_TIMER:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_PRECISION_100NS_TIMER:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_PRECISION_OBJECT_TIMER:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_AVERAGE_TIMER:
case Interop.Interop.Kernel32.PerformanceCounterOptions.PERF_AVERAGE_BULK:
newPdhValue.FirstValue = newSample.RawValue;
newPdhValue.SecondValue = newSample.BaseValue;
oldPdhValue.FirstValue = oldSample.RawValue;
oldPdhValue.SecondValue = oldSample.BaseValue;
break;
default:
// an unidentified counter was returned so
newPdhValue.FirstValue = 0;
newPdhValue.SecondValue = 0;
oldPdhValue.FirstValue = 0;
oldPdhValue.SecondValue = 0;
break;
}
}